To determine the possible relationship between diabetes mellitus and coxsackievirus B infection: a. To examine in the mouse, by histopathologic and fluorescent antibody techniques the relationship between infection with pancreatropic strains of coxsackievirus B and the functional status of the islets of Langerhans. b. To determine in this model, the role of such infection as an initiating or contributing factor in the normal, the genetically susceptible and the environmentally stressed host. c. To examine by fluorescent antibody techniques, autopsy specimens of human pancreas both from known diabetics and nondiabetics, for the presence of coxsackievirus B antigen and for evidence of autoimmune reactions. To correlate the results of these fluorescent antibody studies with results of histopathological examination.